Ammoxidation of alkenes exploits the weak C-H bonds that are located in the
allylic position of unsaturated hydrocarbons.
Benzylic C-H bonds are also susceptible to ammoxidation, reflecting the weakness of their C-H bonds.
Benzonitrile is produced from toluene, and
phthalonitriles are produced from
xylenes. The reaction represents a partial oxidation. Many byproducts are generated, but the feedstocks are often simple, which compensates for these losses. Additionally, some byproducts are useful or recyclable. For the production of acrylonitrile, byproducts include
hydrogen cyanide,
acrolein, and the solvent
acetonitrile.
Typical catalysts are the oxides of vanadium and molybdenum. The original catalyst discovered at Sohio was bismuth phosphomolybdate (BiPMo12O40).[1]π-Allyl complexes are assumed as intermediates.[6][5]
Related processes
Instead of alkenes,
alcohols and
aldehydes are competent substrates:
These substrates are usually more expensive than the alkenes, so they are less common. The
nitrile process is used industrially to produce nitriles from fatty acids: